Spin Drain Cycles for Reduction of Load Tangling in Abbreviated or No Central Column Top Load Laundry Washer

ABSTRACT

In place of a static drain, a final tub spin interval during a wash cycle and/or rinse cycle of a laundry washing machine/process is continued at the time that the main drain of the free liquid in the wash tub is initiated. This spin may continue until completion of the drain and extraction. In one embodiment, the sequence includes a transition from a relatively slow speed spin of a rinse or wash agitation interval to a high speed extraction spin. Thus, the conventional transition from the rinse and/or wash cycle to a static drain is eliminated. In addition, the conventional transition from a static drain to a high-speed extraction spin drain is eliminated. Such a change in the operation sequence of the washer can help reduce tangling and/or balling of the wash load, especially in a washer having an abbreviated or no central column/agitator. Such a change can also reduce associated imbalance during the spin drain, which can benefit machines both with and without a central agitator.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. provisional application Ser. No. 61/073,064, filed Jun. 17, 2008, which is hereby incorporated by reference in its entirety.

BACKGROUND

Automatic washing machines have existed for many years. Conventional automatic washing machines generally include an external cabinet containing a dual tub arrangement in which an inner perforated tub (wash basket) rotates within an outer tub that remains generally stationary. In addition, conventional top-load washing machines typically include a central column that can rotate independently and act as an agitator.

In a typical wash cycle, clothing is loaded into the wash basket. The outer tub and nested wash basket are filled with wash liquid to a predetermined level and the central column agitates the wash load within the liquid to cleanse the clothing. Once the wash cycle is complete, wash liquid is drained from the outer tub via a drain outlet provided therein. The wash basket then rotates (spins) at a high rate of speed to force wash liquid absorbed by the wash load out of the load, through the wash basket apertures and into the outer tub, from which it is drained via the drain outlet.

Washing machines have been proposed that employ tub rotation as a means for agitating the wash load during the wash cycle. For instance, U.S. Pat. No. 5,271,251 to Kovich et al. discloses a tub with at least one ramp on the floor of an inner wash basket (nested within a stationary outer basket). The ramp is configured to be used in conjunction with a baffle mounted to a sidewall of the wash basket. It is apparent that the baffles are located at least partially below the standing water line on the inner surface of the tub. The bottom ramps are positioned to guide the wash load upward and outward, toward the sidewall of the tub, into engagement with the baffle surfaces that then cause the load to tumble around the baffle.

U.S. Pat. No. 5,878,602 to Kovich et al. discloses baffles spaced about a cylindrical wall portion. No bottom ramps are used in the '602 patent. Rather, a rotatable wash plate is nested in the tub bottom and includes a pair of diametrically opposed ripples or ridges. The wash plate imparts a vertical motion to the load as the wash plate is oscillated.

Commonly owned U.S. application Ser. No. 11/610,380, filed Dec. 13, 2006, hereby incorporated by reference in its entirety, discloses an automatic washing machine that includes a frame and a wash basin assembly rotatably mounted within the frame. The wash basin assembly includes a wash basin container having a bottom and sidewalls extending up from the bottom. At least one bottom ramp is affixed to and extends upwardly from the wash basin container bottom and presents an upwardly inclined ramp surface. A drive system is provided for selectively rotatably driving the wash basin container, and a controller is provided for controlling the drive system to repeatedly intermittently rotatably drive and brake the wash basin container during a wash cycle of the washer, to thereby cause the wash basin container to alternatively accelerate and decelerate. At least one sidewall ramp may be affixed to the wash basin container sidewall and present an inwardly inclined ramp surface. The at least one sidewall ramp may be spaced above the top of the at least one bottom ramp.

The acceleration and deceleration causes the at least one bottom ramp to induce a wave wash action on wash liquid within a lower portion of the wash basin container, by liquid flowing over the at least one ramp as the liquid continues to rotate within the wash basin container following an acceleration/deceleration cycle of said wash basin container. The acceleration/deceleration cycle further induces in the wash liquid parabolic water profile formation and collapse actions serving, in conjunction with the at least one sidewall ramp (if provided), to circulate the load so that a portion of the wash load in an upper portion of the wash basin container is circulated to a lower portion of the wash basin container where it can be subjected to the wave wash action induced by the at least one bottom ramp.

Such an arrangement can provide a highly effective and efficient wash action while advantageously eliminating the need for a central agitator and a complex transmission for independently oscillating the central column to agitate the load.

In conventional washing machines, a central auger-like column rotates independent of the wash basin and acts as an agitator to impart a mechanical wash action on the clothes during the wash cycle. In the arrangement shown in application Ser. No. 11/610,380, the mechanical wash action may be accomplished by elements affixed to the wash tub, and intermittent intervals of acceleration and deceleration of the wash tub in opposite directions. Thus, a central column is not required for agitating the wash load. Omission of a central column yields the benefit of increased capacity of the washer and ease of loading and unloading. It has been found, however, that without a central agitator or column, there is a greater tendency for tangling, twisting or balling of the laundry load. Testing has revealed that the clothes loads washed with top load or vertical axis machines lacking a central column or agitator experience a unique set of problems not previously encountered by those washed in traditional central agitator washers. Central agitator machines keep the load from settling to the center due to their basic construction. If a tall central agitator is omitted, the load may settle across the center and ultimately tangle and twist into a large mass which is difficult for the user to remove, and which may inhibit optimal wash and rinse actions. Such a condition may also cause imbalances making a spin at high speed impossible. Additionally, tangling in washers, especially with line drying, contributes to greater wrinkling of the laundry items.

In machines lacking a central agitator or column, a wash methodology/sequence that effectively addresses these problems would be highly desirable.

BRIEF SUMMARY OF SELECTED INVENTIVE ASPECTS

In view of the foregoing, a primary objective of the present invention is to reduce tangling of clothes loads in top-load washing machines, particularly those lacking a tall central agitator or column. This, in turn, can make the transfer to a dryer or clothes line easier, reduce wrinkling of the laundry items in the load, and reduce occurrence of imbalance conditions.

In accordance with an aspect of the invention, in place of a static drain, the final tub spin interval during the wash cycle and/or rinse cycle is continued at the time that the main drain of the wash tub is initiated. This spin may continues until completion of the drain and extraction. In one embodiment, the sequence includes a transition from a relatively slow speed spin of the rinse or wash agitation interval to a high speed extraction spin. Thus, the conventional transition from the rinse and/or wash cycle to a static drain is eliminated. In addition, the conventional transition from a static drain to a high-speed extraction spin drain is eliminated. Instead, a transition from a relatively slow-speed spin to a higher speed extraction spin may be provided. Such a change in the operation sequence of the washer can help reduce tangling and/or balling of the wash load, and also reduce associated imbalance during the spin drain. This latter benefit can also apply to machines which include a central agitator.

This summary is provided to introduce a selection of concepts of the inventive subject matter that are further described below in the detailed description. This summary is not intended to identify essential features or advantages of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Additional features and advantages of various embodiments are further described below.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the invention are illustrated by way of example and not by limitation in the accompanying figures in which like reference numerals indicate similar elements and in which:

FIG. 1 is graph plot illustrating the variability of the forces acting on items of a laundry load in relation to distance from the central axis of tub rotation.

FIGS. 2-5 are perspective views illustrating various states of a laundry load in the case of a washer wash basin lacking a tall central column and employing a conventional sequence of static drain followed by high-speed spin extraction.

FIG. 6 is a front elevational view of an exemplary automatic washing machine to which the inventive aspects described herein may be applied.

FIG. 7 is a cross-sectional view of the automatic washing machine of FIG. 6 taken along line 7-7 shown in FIG. 6.

FIG. 8 is a radial cross-sectional view of an arrangement of a wash basin in accordance with an aspect of the invention, showing side and bottom mounted wash action ramps.

FIG. 9 is a radial cross-sectional view of the wash basin of FIG. 8, rotated 90 degrees.

FIGS. 10A through 10D are sequential perspective views of a wash basin, illustrating sequential wash actions imparted on a load by virtue of the wash action ramps, and a sequence of wash basin accelerations and decelerations, in accordance with aspects of the invention.

FIG. 11 is a graph illustrating an exemplary sequence of wash basin accelerations and decelerations, in accordance with an aspect of the invention.

FIG. 12 is a graph illustrating wash basin rotation speeds over the course of an exemplary overall wash operation in accordance with an aspect of the invention.

FIGS. 13A through 13E are diagrammatic cross-sectional views of a wash basin, illustrating sequential states of a load during a spin drain sequence in accordance with the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The typical wash action routine of a clothes washing machine is generally as follows. First, the wash tub and nested wash basin are filled with water as the wash basin either slowly rotates or remains motionless. Next, wash/agitation rotations/oscillations are initiated. Depending on the type of machine, these may be carried out using a central column or auger-style agitator, an impellor (which is a relatively low profile plate with agitation elements formed thereon, that selectively rotates/oscillates independently of the wash basin), or by rotation/oscillation of the wash basin itself (which may have elements fixedly mounted thereon (e.g., ramps as described and shown in commonly assigned application Ser. No. 11/610,380). Next, a static drain (no motion) is executed to pump out the liquid and any debris. Then comes a high speed spin extraction (spinning to centrifugally dewater the textiles comprising the load). The foregoing process is usually repeated for one or more rinse cycles.

The present inventors observed that with a conventional agitator machine, during the static drain, the clothes slowly descend and arrange themselves in a loose toroid around the agitator post. In contrast, in non agitator machines the load typically spreads to level out to more of a disk shape. As mentioned above, a high speed spin extraction drain traditionally starts after a static drain (no wash basin rotation). Initial removal of the free water in the tub reduces the force needed to rotate the wash basin. While this sequence does not adversely affect the toroid shape of central agitator machines, the opposite has been found to be true in tests conducted on non-agitator machines lacking a tall central column. Large items like a bed sheet, in such machines, will experience uneven forces which pull it radially outward according to the equation:

F=mω²r

Where:

-   -   ω is the rotational speed of the wash basket;     -   r is the radius from the center of rotation;     -   m is mass; and     -   F is the radial force felt at r.

Thus, the forces tend to “pull” greater on masses furthest from center portions as visually graphed in FIG. 1, wherein the number values on the radial lines of the graph represent “r” and the large numbers labeling the concentric rings represent pound-force equivalent figures based on a given hypothetical mass and rpm. This pull results in some interesting phenomena. A large item such as a sheet or towel can be stretched across the top and cause a ‘drum top’ like formation such as shown in the photos of FIGS. 2 and 3. This happens at all strata of the load causing the clothes load to tangle together and in some cases wrap up into a ball during the next agitation cycle leading to the cases illustrated in FIGS. 4 and 5. These cases contribute to poor performance from a tangling perspective. Embodiments of the present invention can be used to substantially improve this situation.

The inventors discovered that substantially reduced tangling and balling of the wash load can be achieved if, in lieu of a static drain following the final rinse agitation (through wash basin rotation), draining is initiated while a speed (e.g., 120 rpm) is maintained which is sufficient to keep the clothing and other load items segregated to the sides of the basin as the water level drops. In one embodiment of the invention, the washer is built so that there is no agitation mechanism clutched to the rotatable wash basket. Rather, the wash/rinse actions are generated by elements (e.g., ramps) fixedly mounted to the rotatable wash basin. Without a central agitator or column, there is no structure to prevent the balling and tangling result illustrated in FIGS. 3-6. The inventors found that initiating and carrying out the drain of free liquid from the wash drum as the basin continues to rotate will keep the clothing segregated to the sides, much as-if a central agitator or column was present.

Based on testing to date, the greatest benefit from the inventive drain sequence is obtained when it is implemented as the final drain sequence, i.e., at the tail-end of the final rinse agitation. This is so because with the final drain sequence there is no further fill and agitate intervals that might serve to detangle the clothes. There is in agitatorless machines more susceptibility to tangling due to static settling followed by acceleration as spinning starts. Nonetheless, some benefit in tangle reduction may also be obtained from implementation of the drain sequence at other (earlier) points in the wash process, e.g., immediately following a non-final rinse agitation phase, or immediately after a wash agitation interval that precedes the first rinse cycle.

With reference to FIGS. 6-7, there is shown one example of an automatic washing machine 100 that may embody various aspects of the invention. Washing machine 100 includes an external generally rectangular cabinet 102, a control panel 104 for controlling the washer operation, and a hinged lid 105 that may be swung open to provide top-load access to a cylindrical wash basin 108 (FIG. 2). As shown in FIG. 2, cabinet 102 is provided as part of a framework 106 that contains a suspended wash group. The wash group includes cylindrical wash basin 108, which is rotatably mounted and configured for containing a wash load and wash liquid. It may be noted that the embodiment illustrated in these FIGS. 6-7 corresponds to the embodiment illustrated in FIGS. 1-2 of commonly owned U.S. application Ser. No. 11/610,380, with the exception of the omission (in the former) of a tall fixedly mounted central column.

In use, after placing a load of laundry in wash basin 108, along with a suitable type and quantity of laundry detergent, a wash process is initiated by an operator through interaction with control panel 104. The process typically begins with a tub fill cycle, wherein water enters the wash basin 108 via an inlet hose, valve and nozzle (not shown). Water fills the wash basin 108 to a predetermined level, which may be varied, e.g., as a user setting and/or depending upon the size of the wash load. Once the appropriate/set level is reached, the water supply valve is closed and the washer enters a wash cycle comprising a number of sequential stages. This wash cycle may include intermittent rotation of the wash basin 108 in one or two directions, i.e., starting and stopping of the rotation of the wash basin 108, to impart, in conjunction with specially configured and placed wash basin-mounted ramps, a highly effective wash action and circulation of the wash load.

Upon completion of the wash cycle, a drain of the wash liquid from the wash basin 108 is carried out via a central drain pipe 114. This may be carried out as a conventional static drain. A static drain is useful because heavy particulate such as sand may have been washed from the clothing but not yet made it to the outer tub—this static draining then tends to flush the debris out of the drum with the evacuating water, perhaps more effectively than would a spin drain. For this reason, it may be desirable to retain at least one static drain (as opposed to a spin drain) following the wash and/or first rinse agitations. Once the free wash liquid (liquid not absorbed into the wash load) pooled within the wash basin 108 is drained, a high speed spin cycle may be initiated wherein the wash basin is rotated at a rate of speed. This rotation of the wash basin 108 forces wash liquid absorbed into the wash load out of the load, and out of the wash basin through the apertures 116 formed in the side of the wash basin 108. The wash load may then be subjected to a rinse cycle, in which the water supply valve is again opened to allow fresh water to enter the wash basin 108. The wash basin is again rotated in one direction and then the other to generate a vigorous rinse action. Thereafter, in accordance with an aspect of the invention, a main drain is carried out during wash basin rotation, followed by an extraction spin drain, as follows. Instead of a conventional static drain following the rinse, the main drain may be carried out as the wash basin continues its rotation in one of the two directions during the rinse cycle following the wash cycle. Once the free wash liquid (liquid not absorbed into the wash load) pooled within the wash basin 108 is drained, a higher speed spin cycle may be initiated wherein the wash basin is rotated at a rate of speed which is substantially higher than the rotation speed used for the wash cycle, in order to extract the rinse liquid from the load.

FIGS. 8 and 9 depict structural aspects of an automatic washing machine, which may be used in an overall wash operation according to the invention. It can be seen that wash basin 400 of FIGS. 8 and 9 includes wash action ramps 402 a, 402 b mounted on the circular bottom and cylindrical sides of the wash basin 400. These ramps serve, in conjunction with a controlled sequence of tub accelerations and decelerations, to impart a wash action and circulation of the load within the wash basin, thus eliminating the need for a central agitator and an associated transmission for permitting the agitator and wash basin to rotate independently. This controlled sequence may be carried out using an electronic controller that may, e.g., be provided as an integral part of control panel 104 shown in FIG. 6. Such a controller may comprise a suitably programmed microprocessor or application specific integrated circuit (ASIC), operably connected to suitable circuitry for driving the wash basin drive motor in accordance with commands of the controller.

One or more wash action ramps 402 a may be molded into or otherwise attached to the bottom of wash basin 400 and have a generally triangular transverse cross-section. Although excellent results have been obtained with a single wash action ramp 402 a affixed to the bottom of the tub and offset from the axis of rotation, in the illustrated arrangement three wash action ramps are located on the bottom of the tub in equi-spaced relationship about the axis of rotation. Alternatively, a second wash action ramp 402 a may be positioned on the bottom of the wash basin 400 at a position radially opposed to the first. Preferably, the ramp structures are positioned so as to provide a center of gravity coinciding with the axis of rotation. This advantageously provides balance during high speed tub spins without the need for any additional counterbalancing structure.

As the wash basin 400 begins to accelerate at the outset of a wash action control sequence, the wash action ramps 402 a sweep through the initially static pool of wash liquid to impart a wave wash action on the wash liquid. This action is, by virtue of water shear, generally confined to a lower portion of the wash basin 400. This is the first component of a mechanical wash action and contributes to good mixing of the wash load in the lower half of the wash basin 400. Additional wave wash action occurs when the wash basin 400 decelerates. While the water mass is rotating with the basin, a subsequent deceleration of the wash basin causes the rotating mass of water to sweep over the ramps as they slow down and stop. Overall, the movement of the ramp 402 a relative to the water creates a wave turbulence that flexes the wash load to impart an excellent wash action.

As illustrated in FIGS. 8 and 9, at least one additional wash action ramp 402 b may be affixed at an upper portion of the sidewall of the wash basin 400. In one embodiment, these sidewall ramps are positioned above what would be expected to be the standing water line for a typical load size. Positioning the sidewall ramps 402 b above the standing water line reduces water-induced drag during spins of the wash basin, and increases load capacity in the lower part of the wash basin. However, the sidewall wash action ramp 402 b may become partially submerged, especially in the case of an extremely large wash load.

The cross-sectional views of FIGS. 8 and 9 illustrate a wash basin configuration having three lower wash ramps 402 a working in conjunction with three upper wash ramps 402 b. In this specific embodiment, an equal number of lower ramps 402 a and upper wash ramps 402 b are provided, and the lower wash ramps 402 a are offset from the upper wash ramps 402 b. As illustrated, each of the ramps has a symmetrical shape (e.g., of an equilateral triangle) providing a pair of opposed ramp surfaces, each being operative to create a wave wash action for a given direction of basin rotation. In an alternate arrangement, the ramps may have an asymmetrical shape to aid in control of a cycle. For instance, a less substantial angle on one side of the ramp may be favored as the face primarily impacted against the water mass during wash basin accelerations and/or decelerations when used with a gentle cycle, while the other side may have a more severe angle which will be favored (in the same sense) when used with a normal cycle. More specifically, the wash basin accelerations and decelerations may be tailored to make the most advantageous use of differing shape profiles provided on opposite sides of the ramps, for providing cycle control.

An arrangement of wash action ramps as described may be implemented in a washing machine having a conventional dual tub arrangement. FIGS. 10A-10D illustrate the wash action ramps aspects of the invention as generally applied to a wash basin that includes a conventional sealed stabilizing ring 620. This wash basin could be a perforated wash basin intended to be nested within a stationary outer splash tub in a conventional manner. Alternatively, wash basin 600 may be equipped with the inventive flow channels 306 and reservoir 404 described in detail in commonly owned application Ser. No. 11/610,380, in which case an outer tub could be omitted.

FIGS. 10A-10D sequentially illustrate the wash action imparted on a wash load using the wash action ramps 602 a, 602 b and a sequence of tub rotation acceleration and deceleration intervals. In FIG. 10A, the wash cycle begins by filling the bottom of the wash basin 600 with a wash liquid 608 to an appropriate level. In the arrangement of FIG. 10A, a low water level, corresponding to a small wash load, is shown to clearly depict the wave action imparted on the wash load. Of course, it is expected that higher water levels corresponding to larger wash loads would also be used. The balls 604 a, 604 b diagrammatically represent items of a wash load. Once the wash basin 600 is filled to a predetermined level with wash liquid 608, the wash basin 600 is accelerated to spin at a high rate. As illustrated in FIG. 10A, the wash basin 600 initially spins in a counter-clockwise direction.

With reference to FIG. 10B, as the wash basin 600 accelerates, the inertia of the wash liquid 608 causes the wash liquid 608 to initially resist rotation with the basin 600. This causes the leading faces of the bottom wash action ramps to impart a large wave action on the wash liquid 608. A wave 606 is diagrammatically illustrated. The three bottom wash action ramps 602 a are spaced equidistant around the bottom surface of the wash basin 600 to induce a multi-peaked wave action throughout the entire lower portion of the wash basin 600. This wave action provides a first component of an induced mechanical wash action, and causes the wash load 604 a, 604 b to flex around and over the ramps 602 a to provide excellent washing action as the ramps sweep through the water mass. An additional component of the wash action occurs because the moment of inertia of the wash load 604 a, 604 b is different from that of the wash liquid 608. As a result of this difference, additional wash action occurs in the form of relative fluid flow over and through the wash load 604 a, 604 b as the water mass begins to rotate relative the wash load.

With reference to FIG. 10C, as the speed of the rotation of the wash basin 600 increases, and friction causes the water mass to rotate with the wash basin, centrifugal force causes the wash liquid 608 to flow outward toward the wall of the wash basin 600. As the speed accelerates above 1G, the wash liquid 608 climbs the sidewall proportionately to rω², where r is the radius of the wash basin 600 and ω is the angular velocity of the wash basin 600. As the wash liquid 608 approaches the same speed of rotation as the wash basin 600, the wash liquid 608 will take on a parabolic profile. At this speed, the wash liquid 608 height may reach the upper wash action ramps 602 b which, as previously mentioned, are preferably positioned above the standing water line. The distribution caused by the parabolic shape encourages a mixing and circulation of the wash load 604 a, 604 b. In particular, as the water takes on a parabolic shape, the water level rises along the sidewall and carries with it a portion of the wash load 604 a, 604 b.

With reference to FIG. 10D, rotation of the wash basin 600 is abruptly decelerated to a stop, causing additional components of a mechanical wash action to occur. First, at the moment of braking, the sidewall mounted ramps 602 b present guide surfaces that encourage an upper portion of the wash load 604 a, 604 b to move inwardly, toward the wash basin's 600 center of rotation, where it will tend to drop (circulate) toward the bottom.

In addition to the sidewall ramp induced circulation and wash action generated upon the wash basin spin deceleration, the parabolic shape of the wash liquid 608 will dramatically collapse, causing mixing of the load. In particular, the collapse of the parabola causes the wash liquid 608 to rush down the sidewall of the wash basin 600 and up, into the center of the wash basin 600, where momentum carries the liquid (and the load) upwardly along the central column. In addition to circulating the load, the collapsing wash liquid 608 causes the wash load 604 a, 604 b to continue to mix and circulate as the wash liquid 608 rushes down the sidewall and up, into the center of the wash basin 600. In one arrangement, excellent mixing occurs when the parabola is driven as high as possible up the sidewall using rapid acceleration, and a strong forceful collapse of the parabola is precipitated by rapid braking.

Also, at the point of deceleration, the inertia of the wash load 604 a, 604 b causes the wash liquid and wash load 604 a, 604 b to continue to rotate longer than the wash basin 600, thereby inducing a wave wash action similar to that induced with the acceleration of wash basin 600. The relative motion of the ramps, the wash liquid and the wash load causes the wash load 604 a, 604 b to flex and flow over and around the ramps, and wash liquid to flow through the wash load, thereby providing an excellent multi-component wash action. As the size of the load increases, the size of the parabola generally decreases. Thus, with a large load, the sidewall ramps assume a relatively greater role in mixing/circulating of the load.

The wash action illustrated in FIGS. 1A-10D may be repeated over and over a number of times for the duration of the wash cycle.

In a preferred arrangement, the wash basin 600 is caused to alternately, successively rotate in opposing directions. For instance, the wash basin may rotate counter-clockwise then come to an abrupt stop. The following wash action may begin with the wash basin rotating in a clockwise direction, then coming to an abrupt stop, and so on. The wash cycle may continue in this manner of rotation for the duration of the wash cycle, or a portion thereof. Such spin patterns may be used in conjunction with differing ramp surface profiles to achieve cycle control, as previously described.

The graph of FIG. 11 provides an example of successive spin tub (wash basin) acceleration and deceleration cycles as described. As is shown, a cycle begins with rapid rotational acceleration of the wash basin in the clock-wise (CW) direction. Once the desired speed of rotation is achieved, the rotation is briefly held at that speed before it is rapidly decelerated. Once the wash basin has stopped rotating, the rotation of the wash basin is again rapidly accelerated, however in an opposite direction, in this case counter-clockwise (CCW). The rotation speed is maintained for an interval and then is rapidly decelerated, as before. Once the rotation has stopped, the wash basin is again accelerated in the first direction (CW). The successive high speed tub rotations, in conjunction with the bottom and sidewall wash action ramps, can provide a highly effective method of washing a laundry load, in lieu of the conventional arrangement of a central, independently rotatable agitator.

In one arrangement, each complete cycle may last between 3 and 15 seconds. For example, one cycle may be approximately 9 seconds, allowing for approximately six cycles per minute. An extremely short cycle could comprise an acceleration phase of 1.5 seconds and a braking (deceleration) phase of 1.5 seconds, for a half-cycle time of three seconds (direction would then change and half cycle would repeat). A more typical half-cycle could comprise, sequentially, an acceleration phase of 5 seconds, a pause phase of 2.5 seconds, a braking (deceleration) phase of 5 seconds and another pause phase of 2.5 seconds, providing a half-cycle time of 15 seconds (direction would then change and half-cycle would repeat). For a single tub arrangement, a wash agitation cycle may last, in total, from 10 to 18 minutes. Additional cycles will occur during the rinse portion of the wash process. This rinse cycle time may vary depending on the cycle setting selected, e.g., 4 to 8 minutes. In one example, the rinse cycle is approximately 5 minutes.

Once the sequence of tub accelerations and decelerations comprising the wash cycle is complete, the wash liquid 608 (the “free” water pooled within the wash basin 600) may be drained through a central drain, or a drain offset on the bottom of an outer splash tub. Whereas previously, this would have been conducted as a static drain, in accordance with the present invention, the drain takes place without interruption of the final spin of the tub during the rinse (or wash) agitation cycle. In other words, there is a smooth transition into a two stage spin drain sequence following an iteration of the “wash with drum” rinse (or wash) agitation interval, e.g., as shown in FIG. 10C.

In an exemplary embodiment, the two stage spin drain process consists of a relatively low speed spin drain cycle that drains the free water from the wash basin as the basin continues to rotate at the same speed, and after that a second high speed spin extraction stage that dewaters the wash load further, in the nature of a conventional spin drain. The period during which the splash tub is non-moving, i.e., static, which would ordinarily separate the final wash or rinse cycle from the high speed spin drain cycle is eliminated. Instead, the drain pump is actuated to allow the wash liquid to begin to drain during a period of splash tub rotation that carries directly over from a stage of the preceding wash or rinse agitation cycle. As can be seen in FIG. 10C, at this point in the process, the wash liquid takes on a generally parabolic shape due to the centrifugal force, and correspondingly the wash load (represented by balls 604 a, 604 b) is raised up and pressed against the sides of the wash basin.

An exemplary overall wash process in accordance with the invention is graphically illustrated in FIG. 12. The time units on the x-axis are minutes. Therein, it can be seen that during a wash agitation phase, the wash basin alternates (accelerates and decelerates) between clockwise and counter-clockwise rotations reaching close to 100 rpm. Immediately following the wash agitation phase is a conventional static drain phase (no wash basin rotation), which is followed by brief high speed spin at 400 rpm. Thereafter, the process enters a rinse agitation phase which substantially mirrors the wash agitation phase, but is shorter in duration. Following this phase, it can be seen that the process smoothly transitions into a two phase spin drain process. The first phase of the drain is a drain of the free water carried out as the wash basin is rotated at a relatively low rpm (as illustrated, close to 100 rpm). This rotation essentially represents a continuation of the last interval of rotation in the rinse agitation phase, which continues for a fixed time interval after which substantially all of the free water is removed. At that point, the process transitions to the second stage of the drain, a high speed final spin extraction phase carried out at 700 rpm, serving to dewater the textile items of the laundry load.

FIGS. 13A-E diagrammatically depict sequential states of a wash load within the rotating wash basin (lacking a central column or agitator) during a drain sequence in accordance with the invention. The hatched regions represent water, and the balls are representative of laundry load items. The state of FIG. 13A occurs at the initiation of the drain, which coincides with the last rotation interval of the rinse agitation phase. At this time, the wash basin is rotating at a speed sufficient to form a generally parabolic water profile within the wash basin. The laundry load (represented by balls) has risen with the water parabola along the sidewalls of the basin, and due to the centrifugal force, the load remains distributed in a generally torroidal configuration against the sidewalls as the water level drops. This is progressively illustrated in FIGS. 13B-13D. In FIG. 13E, all of the free water has been drained from the basin, and the basin continues to rotate so as to maintain the load distributed in a generally torroidal shape against the sidewalls of the basin. At this point, the rotation speed may be ramped up to directly enter the high-speed spin extraction phase. With the load distributed in a generally toroidal shape against the sidewalls of the basin at the initiation of the high-speed spin extraction, such an even distribution can persist during the high-speed spin and thus result in reduced tangling upon completion of the overall wash process. Relatedly, the imbalance conditions that can accompany tangling and balling of the clothes load, which can substantially impede or render impossible a high-speed spin, can be reduced or eliminated. Testing has shown that the two-stage spin drain of the present invention can also provide improvements in load distribution in washing machines that include a central agitator or column, thus leading to a reduction in the occurrence and/or severity of imbalance conditions in this case as well. Such an application is considered to be an aspect of the present invention.

The invention has been described in terms of particular exemplary embodiments. Numerous other embodiments, modifications and variations within the scope and spirit of the invention will occur to persons of ordinary skill in the art from a review of this disclosure. 

1. An automatic washing machine, comprising: a frame; and a wash basin rotatably mounted within the frame, the wash basin having a bottom and sidewalls extending up from said bottom; a drive system for selectively spinning said wash basin; a drain system for automatically draining the wash basin of wash liquid therein; and control means for controlling said drive system to selectively spin the wash basin and for controlling said drain system to selectively drain the wash basin of said wash liquid, said control means being configured to initiate a drain of free wash liquid in the wash basin while the wash basin is being spun by the drive system.
 2. An automatic washing machine according to claim 1, wherein the drain of the wash basin is initiated during a period of spinning of the wash basin and free liquid therein, continued from a spin interval of a wash cycle or rinse cycle of the washing machine.
 3. An automatic washing machine according to claim 2, wherein said spin interval is a final spin interval of said wash cycle or rinse cycle.
 4. An automatic washing machine according to claim 1, wherein said control means is further configured to continue to spin the wash basin to completion of the drain of free liquid from the wash basin.
 5. An automatic washing machine according to claim 4, wherein said control means is further configured to transition from a relatively slow speed spin at initiation of the drain of free liquid from the wash basin, directly into a relatively high speed extraction spin interval during which wash liquid absorbed within a wash load is extracted and drained from the wash basin.
 6. An automatic washing machine according to claim 1, wherein the wash basin lacks a central agitator or column rising substantially from the bottom of the wash basin.
 7. An automatic washing machine according to claim 1, wherein said rotatable wash basin has fixedly mounted thereon at least one wash/rinse action generating element.
 8. An automatic washing machine according to claim 7, wherein said at least one wash/rinse action generating element comprises a ramp structure.
 9. An automatic washing machine according to claim 1, wherein said control means is configured to carry out the drain of free liquid while a rotation speed of the wash basin is maintained which is sufficient to keep laundry load items within the wash basin segregated to the sides of the basin as the free liquid level drops.
 10. An automatic washing machine according to claim 1, wherein said control means is configured to cause said wash basin to alternately, successively, rotate in opposing directions during a wash or rinse agitation cycle, and initiation of the drain of free liquid from the wash basin takes place without interruption of the final spin of the tub during the rinse or wash agitation cycle.
 11. A method of washing a load of laundry using an automatic washing machine, comprising: placing a load of laundry within a wash basin rotatably mounted within a frame, said wash basin having a bottom and sidewalls extending up from said bottom; dispensing wash liquid into said wash basin containing said load of laundry; selectively spinning said wash basin, including said wash liquid and laundry; and initiating a drain of free wash liquid from the wash basin while the wash basin is being spun.
 12. A method according to claim 11, wherein the drain of free wash liquid from the wash basin is initiated during a period of spinning of the wash basin and free liquid therein, continued from a spin interval of a wash cycle or rinse cycle of the washing machine.
 13. A method according to claim 12, wherein said spin interval is a final spin interval of said wash cycle or rinse cycle.
 14. A method according to claim 11, wherein said period of spinning of the wash basin continues to completion of the drain of free liquid from the wash basin.
 15. A method according to claim 14, further comprising transitioning from a relatively slow speed spin at initiation of the drain of free liquid from the wash basin, directly into a relatively high speed extraction spin interval during which wash liquid absorbed within the wash load is extracted and drained from the wash basin.
 16. A method according to claim 11, wherein the drain of free liquid is carried out while a rotation speed of the wash basin is maintained which is sufficient to keep the load of laundry within the wash basin segregated to the sides of the basin as the free liquid level drops.
 17. A method according to claim 11, further comprising causing said wash basin to alternately, successively, rotate in opposing directions during a wash or rinse agitation cycle, and wherein the initiation of the drain of free liquid from the wash basin takes place without interruption of the final spin of the tub during the rinse or wash agitation cycle.
 19. A method according to claim 11, wherein initiation of the drain of free wash liquid occurs when the wash basin is rotating at a speed sufficient to form a generally parabolic wash liquid profile within the wash basin, the laundry load has risen with the water parabola along the sidewalls of the basin, and due to the centrifugal force, the load remains distributed in a generally torroidal configuration against the sidewalls as the water level drops.
 20. A method according to claim 19, further comprising, after the free wash liquid has been substantially drained from the basin, causing the wash basin to continue to rotate so as to maintain the load distributed in said generally torroidal shape against the sidewalls of the basin, then ramping the rotation speed up to directly enter the high-speed spin extraction phase. 